A casement or an awning window generally refers to a sash that is attached to its frame by one or more hinges. The hinges can be located on any side of the sash and the frame though generally not on the lower edge of the sash and frame. In general, a casement window rotates along a horizontal plane (the hinges of a casement window defining a vertical rotation axis), while an awning window rotates along a vertical plane (the hinges of an awning window defining a horizontal rotation axis). Most casement and awning windows which employ the use of a crank lever or cam handle operator open outwardly so as not to interfere with the operator of the window.
An advantage of many casement and awning windows is that substantially the full window opening can be exposed without requiring the removal of the window from the frame. In contrast, for example only half of the opening of a double-hung window can be exposed by raising the lower sash or lowering the upper sash. The sashes of double hung or horizontally sliding windows must be completely removed from the frame to expose the entire window opening.
Manufacturers of windows continue to provide higher performance windows having higher design performance. At the same time, manufacturers of windows seek ways to simplify the manufacturing process to reduce complexity.
Keepers are secured to either to the sash or the window frame and are engaged by a locking mechanism to secure the window in a closed position. Keepers must capture and hold a lock point in extreme performance conditions. These extreme performance conditions include high wind loading, as well as conditions that may occur to the window during shipping, handling and installation. Under these circumstances, high stresses may be placed on the window sash within the frame, which tend to force the window toward an open position.
Casement and awning windows are manufactured in a wide variety of profiles and materials. Casement and awning windows may be manufactured with wood, vinyl, aluminum or composite sashes and frames. This variability of window design and component materials presents challenges to keeper application and performance.
In general, current keeper designs provide good window performance in real application situations as well as test environments so long as the windows are structurally sound. Variability in window profiles, especially when window structures are formed of vinyl, can provide considerable challenges to design and strength requirements for a locking mechanism.
Some keepers may provide desired performance but require complicated jigs for proper positioning. Other prior art keepers may function appropriately and have desired features, but the structure of the keeper in combination with the strength profile of the material from which the window members are made sometimes permits window members to rotate or twist thus disengaging the locking mechanism from the keeper. This disengagement can cause the window to fail under high stress conditions. In some circumstances, a keeper may provide sufficient function and performance but be aesthetically unacceptable or may require complicated installation or may require a particular placement of the hardware that is undesirable to window manufacturers.
There exist in the prior art some non-handed low profile keepers which include a self-locating feature. A non-handed keeper is a keeper that can be used either in a right handed or left handed window without the need for two separate keepers for right handed and left handed windows.
Unfortunately, some of these keeper designs, when applied to a less rigid frame member, can be subject to separation. When the window is closed and locked, the keeper engages a lock lug. In some window structures having lesser rigidity, when subject to stress, the window sash can deflect causing a sash or frame member to rotate, which in turn causes the locking lug to disengage from the keeper, thus releasing the window sash from the frame in the lock position.
The prior art includes some non-handed keepers formed in a C-shape. These keepers lack a self-locating feature and have screw hole locations in the center of the keeper which may make for awkward installation.
Some prior art keepers also have a steep ramp angle where the locking lug enters the keeper. The steep ramp angle can make operation of the keeper difficult in that it is hard to engage the locking lug within the keeper. Further, these prior art keepers generally require a fixture or jig in the factory to be properly located on the window sash or window frame.
Other known prior art keepers are either handed in that they must be produced in left or right handed versions depending upon their application or lack in self-locating features thus requiring a jig or fixture for installation. Accordingly, there is still room for improvement in the area of window hardware involved in casement and awning window keepers and locking lug engagement devices.